Cold stress strongly hinders plant growth and development. However, the molecular and physiological adaptive mechanisms of cold stress tolerance in plants are not well understood. Plants adopt several morpho-physiological changes to withstand cold stress. Plants have evolved various strategies to cope with cold stress. These strategies included changes in cellular membranes and chloroplast structure, regulating cold signals related to phytohormones and plant growth regulators (ABA, JA, GA, IAA, SA, BR, ET, CTK, and MET), reactive oxygen species (ROS), protein kinases, and inorganic ions. This review summarizes the mechanisms of how plants respond to cold stress, covering four main signal transduction pathways, including the abscisic acid (ABA) signal transduction pathway, Ca²⁺ signal transduction pathway, ROS signal transduction pathway, and mitogen-activated protein kinase (MAPK/MPK) cascade pathway. Some transcription factors, such as AP2/ERF, MYB, WRKY, NAC, and bZIP, not only act as calmodulin-binding proteins during cold perception but can also play important roles in the downstream chilling-signaling pathway. This review also highlights the analysis of those transcription factors such as bHLH, especially bHLH-type transcription factors ICE, and discusses their functions as phytohormone-responsive elements binding proteins in the promoter region under cold stress. In addition, a theoretical framework outlining plant responses to cold stress tolerance has been proposed. This theory aims to guide future research directions and inform agricultural production practices, ultimately enhancing crop resilience to cold stress.

Proteome analysis of grafted cotton exposed to low-temperature stress can provide insights into the molecular mechanistic of chilling tolerance in plants. In this study, grafted and non-grafted cotton plants were exposed to chilling stress (10 °C/5 °C) for 7 d. After the stress, rootstock and scion samples were labeled by 8-plex iTRAQ (isobaric Tags for Relative and Absolute Quantification), followed by two-dimensional liquid chromatography separation and tandem mass spectrometry identification. In total, 68 differential proteins were identified that were induced by low-temperature stress and grafting, and these proteins regulate physiological functioning. Under low-temperature stress, in the cotton seedlings, the proteins responded to the MAPK signaling pathway and calcium signaling pathway enhanced, the metabolisms of carbohydrate, lipid, nucleotide, and amino acid had a tendency to intensify, the proteins related to protein folding and degradation were activated, along with the system of antioxidant enzymes to offset cellular oxidative damage. In contrast, chilling stress reduced oxidative phosphorylation, photosynthesis, and carbon fixation. These data indicated that the physiological changes in cotton seedlings comprise a complex biological process, and the ability of plants to resist this stress can be improved after grafting onto a vigorous rootstock, although this was not obvious in the young plants. Further studies of low-temperature stress and/or graft-related differences in proteins could lead to the identification of new genes associated with chilling tolerance in plants. These data provide the basis for further studies on the molecular mechanism of chilling tolerance and the relationship of grafting and chilling tolerance in cotton.